Electrolytic capacitor

ABSTRACT

The electrolytic capacitor has an insulating casing, at least one capacitor element and multiple external terminals. The casing has multiple through holes and mounting protrusions. The at least one capacitor element is mounted in the casing and has multiple inner conductive pins connecting to a coil. Each external terminal is attached to a bottom panel of the insulating casing, connects to a corresponding inner conductive pin and has a main body, a connecting portion and two fixing portions. The connecting portion is formed on and extends from a side of the main body and has a conducting hole attached to a corresponding conductive pin. The fixing portions respectively extend from two ends of the main body and engage with the mounting protrusions. Each external terminal provides a soldering surface being flat and having large soldering area, therefore the electrolytic capacitor can be firmly soldered on a circuit board.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrolytic capacitor, especiallyto an electrolytic capacitor having external terminals with easilysecured and soldered conductive pins not requiring excessive working soreducing defects.

2. Description of the Related Art

A conventional electrolytic capacitor may be packaged with a metalcasing or an insulating casing and may have conductive pins beingconnected to the casing and bent into an L-shape or flattened. Butbending or flattening may cause stress fractures in the conductive pinsand lower the reliability of the electrolytic capacitor. Besides, themanufacturing process of the electrolytic capacitor has a hightemperature heating step that may easily cause carbonization of soldercoatings of the conductive pins and lower the solderability of theconductive pins.

Furthermore, the conductive pin of the conventional electrolyticcapacitor provides a small soldering area due to having a thin andnarrow shape. The L-shaped conductive pin is easy to be deformed byexternal forces and makes the electrolytic capacitor unable to bemounted on a corresponding position of a circuit board. Moreover,connection between the L-shaped conductive pin and the casing is notshock endurable also raising probability of defects.

To overcome the shortcomings, the present invention provides anelectrolytic capacitor to mitigate or obviate the aforementionedproblems.

SUMMARY OF THE INVENTION

The main objective of the invention is to provide an electrolyticcapacitor having external terminals with easily secured and solderedconductive pins not requiring excessive working so reducing defects.

The electrolytic capacitor in accordance with the present inventioncomprises an insulating casing, at least one capacitor element andmultiple external terminals.

The insulating casing has a base and a cover. The base has a topopening, a bottom panel, a chamber, multiple mounting protrusions andmultiple through holes. The cover is mounted on the top opening of thebase.

The at least one capacitor element is mounted securely in the insulatingcasing and has a coil and multiple inner conductive pins. The coil isdisposed in the chamber of the base. The inner conductive pins aremounted on a bottom end of the coil and respectively extend through thethrough holes of the base.

The external terminals are attached to the bottom panel of the base andrespectively connect to the inner conductive pins of the at least onecapacitor element. Each external terminal has a main body, a connectingportion and two fixing portions. The connecting portion is formed on andextends from a side of the main body and has a conducting hole attachedto a corresponding conductive pin. The fixing portions respectivelyextend from two ends of the main body and engage with the mountingprotrusions of the base.

Compared with conventional electrolytic capacitor, the present inventionis capable of being soldered well and enhanced stability of solderingwhen using surface mounting technique (SMT). Because the externalterminal and capacitor element are made separately, solder coating ofthe external terminal is not carbonized by a high temperature heatingstep of the manufacturing process of the capacitor element. Thereforetaking the external terminals as the soldering part of the electrolyticcapacitor can be soldered well.

With the foregoing structure of external terminals, the electrolyticcapacitor provides soldering surfaces that are flat and have largesoldering areas, therefore the electrolytic capacitor can be firmlysoldered on a circuit board by using surface mount technique (SMT).Since the structure provides multiple fixing points between the externalterminals and the insulating casing, the external terminals endureshocks and are not easily deformed by external forces.

Other objectives, advantages and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a first embodiment of anelectrolytic capacitor in accordance with the present invention;

FIG. 2 is a perspective view of the electrolytic capacitor in FIG. 1;

FIG. 3 is a cross sectional side view of the electrolytic capacitor inFIG. 2 embodied as a solid electrolytic capacitor;

FIG. 4 is a cross sectional side view of the electrolytic capacitor inFIG. 2 embodied as a liquid electrolytic capacitor;

FIG. 5 is a perspective view of a production process of the electrolyticcapacitor in FIG. 2;

FIG. 6 is a partially exploded, perspective view of a second embodimentof the electrolytic capacitor in accordance with the present invention;

FIG. 7 is a perspective view of the electrolytic capacitor in FIG. 6;

FIG. 8 is a partially exploded, perspective view of a third embodimentof the electrolytic capacitor in accordance with the present invention;

FIG. 9 is a perspective view of the electrolytic capacitor in FIG. 8;

FIG. 10 is a partially exploded, perspective view of a fourth embodimentof the electrolytic capacitor in accordance with the present invention;and

FIG. 11 is a perspective view of the electrolytic capacitor in FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, 2, 6 to 11, an electrolytic capacitor inaccordance with the present invention comprises an insulating casing(10), at least one capacitor element (20) and multiple externalterminals (30).

With further reference to FIGS. 3 and 4, the insulating casing (10) hasa base (11) and a cover (12). The base (11) has two opposite sidewalls,a top opening, a bottom panel, a chamber (13), multiple through holes(16), multiple optional mounting recesses (15) and multiple mountingprotrusions (14). The bottom panel is adjacent to the sidewalls. Thethrough holes (16) are formed through the bottom panel and communicatewith the chamber (13). The mounting recesses (15) are formed on theopposite sidewalls of the base (11) and extend to the bottom panel ofthe base (11). The mounting protrusions (14) are formed on the base (11)and may be formed on the bottom panel of the base (11) or respectivelyformed in the mounting recesses (15).

When formed in the mounting recesses (15), the mounting protrusions (14)may protrude form the mounting recesses (15) and have two sides and maybe oblique to the mounting recesses (15) and thereby form an inclinedsurface.

The cover (12) enclosing the top opening of the base (11) and may bemade of plastic or aluminum and be mounted on the base (11), or thecover (12) may be a sealing gel solidifying after being applied over thetop of the base (11).

The at least one capacitor element (20) is mounted securely in theinsulating casing (10) and has a coil (21) and multiple inner conductivepins (22). Depending on design requirements, the electrolytic capacitormay have one capacitor element (20) as shown in FIGS. 1 to 9 or multiplecapacitor elements (20) as shown in FIGS. 10 and 11. The coil (21) isdisposed in the chamber (13) of the base (11) and has a bottom end. Thecoil (21) may be formed by winding an anode foil, a cathode foil and anisolating layer between the anode and cathode foils. When theelectrolytic capacitor of the present invention is a solid stateelectrolytic capacitor, the at least one capacitor element (20) may havea conductive polymer electrolyte applied on and around the anode andcathode foils. When the electrolytic capacitor of the present inventionis a liquid state electrolytic capacitor, the chamber (13) of the base(11) may be filled with an electrolytic solution. The inner conductivepins (22) are mounted on the bottom end of the coil (21) andrespectively extend through the through holes (16) of the base (11) andmay be respectively connected to the anode and cathode foils.

The external terminals (30) are mounted to the bottom panel of the base(11) and respectively connect to the inner conductive pins (22) of theat least one capacitor element (20). Each external terminal (30) has amain body (31), a connecting portion (32) and two fixing portions (34).

The main body (31) has a side and two ends.

The connecting portion (32) is formed on and extends from the side ofthe main body (31) and has a conducting hole (33) attached to acorresponding inner conductive pin (22).

The fixing portions (34) respectively extend from the ends of the mainbody (31) and engage the mounting protrusions (14) of the base (11).Each fixing portion (34) may have a fixing hole (35 a) attached to acorresponding mounting protrusion (14) when the mounting protrusions(14) are formed on the bottom of the base (11).

When the mounting protrusions (14) are formed in the mounting recesses(15), each fixing portion (34) may extend perpendicularly from the endsof the main body (31). The fixing portions may have an engaging hole (35b, 35 c) mounted around and engaging a corresponding mounting protrusion(14). When the mounting protrusions have the inclined surface, thefixing portions (34) are respectively slid along the inclined surfacesof the mounting protrusions (14) and hooked over the mountingprotrusions (14) by the engaging holes (35 b).

Further, the engaging holes (35 c) may be formed through ends of thefixing portions (34) to form clamping arms, each clamping arm mayfurther have a boss protruding therefrom and clamping a correspondingmounting protrusion (14) when mounted on the mounting protrusions (14)of the base (11).

With further reference to FIG. 5, during manufacture, the innerconductive pins (22) have a surplus length which is cut to a suitablelength after extending through the through holes (16) of the base (11).The external terminals (30) then correspondingly connect to the innerconductive pins (22) with the conducting holes (33).

Each external terminal (30) provides a soldering surface that is flatand has a large soldering area and so can be soldered well; thereforethe electrolytic capacitor can be firmly soldered on a circuit boardusing surface mount technique (SMT). Since the structure providesmultiple fixing points between the external terminals (30) and theinsulating casing (10), the external terminal (30) is shock endurableand is not easily deformed by external forces.

Even though numerous characteristics and advantages of the presentinvention have been set forth in the foregoing description, togetherwith details of the structure and features of the invention, thedisclosure is illustrative only. Changes may be made in the details,especially in matters of shape, size, and arrangement of parts withinthe principles of the invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed.

1. A electrolytic capacitor comprising: an insulating casing having abase having two opposite sidewalls; a top opening; a bottom panel beingadjacent to the sidewalls; a chamber; multiple through holes beingformed through the bottom panel and communicating with the chamber; andmultiple mounting protrusions formed on the base; and a cover enclosingthe top opening of the base; at least one capacitor element beingmounted securely in the insulating casing and having a coil beingdisposed in the chamber of the base and having a bottom end; andmultiple inner conductive pins being mounted on the bottom end of thecoil and respectively extending through the through holes of the base;and multiple external terminals being mounted on the bottom panel of thebase, respectively connecting to the inner conductive pins of the atleast one capacitor element and each external terminal having a mainbody having a side and two ends; a connecting portion being formed onand extending from the side of the main body and having a conductinghole attached to a corresponding conductive pin; and two fixing portionsrespectively extending from the ends of the main body and engaging themounting protrusions of the base.
 2. The electrolytic capacitor asclaimed in claim 1, wherein the mounting protrusions are formed on thebottom panel of the base; and each fixing portion of the externalterminals has a fixing hole attached to a corresponding mountingprotrusion.
 3. The electrolytic capacitor as claimed in claim 1, whereinthe base of the insulating casing further has multiple mounting recessesformed on each sidewall of the base and extending to the bottom panel ofthe base; the mounting protrusions of the base are respectively formedin the mounting recesses; and each fixing portion of the externalterminals extends perpendicularly from the ends of the main body and hasan engaging hole mounted around and engaged a corresponding mountingprotrusion.
 4. The electrolytic capacitor as claimed in claim 3, whereinthe engaging holes are formed through ends of the fixing portions andclamp a corresponding mounting protrusion.
 5. The electrolytic capacitoras claimed in claim 1, wherein the cover of the insulating casing ismade of plastic.
 6. The electrolytic capacitor as claimed in claim 1,wherein the cover of the insulating casing is made of aluminum.
 7. Theelectrolytic capacitor as claimed in claim 1, wherein the cover of theinsulating casing is a sealing gel solidifying after being applied overthe top opening of the base.
 8. The electrolytic capacitor as claimed inclaim 3, wherein each mounting protrusion is oblique to the mountingrecesses and thereby form an inclined surface.